Phenolic resins using polyamines and polyethers in their production

ABSTRACT

Phenolic resins obtained by condensation from alkylphenol, aldehyde, polyamine and polyether in a molar ratio of 1:0.7 to 1.3:0.005 to 0.2:0.001 to 0.3 are suitable as tackifiers for rubber mixtures.

This invention relates to phenolic resins obtained from alkylphenol,aldehyde, polyamine and polyether.

In the fabrication of rubber articles, such as tires, rollers and hoses,the individual rubber mixtures united with one another have to adherefirmly so that they do not separate from one another again beforeforming by molding and vulcanization.

Rubber mixtures often show inadequate fabrication tackiness.Accordingly, a tackifier has to be added to the rubber mixtures beforeprocessing. In addition to maximum effectiveness, tackifiers must becompatible both with the rubbers and with the other constituents of themixtures and must not have any significant adverse effect uponprocessing, vulcanization, ageing and the physical properties of thevulcanizate.

Tackifying resins of monosubstituted phenols, aldehydes and aliphatic orcycloaliphatic polyamines containing at least two primary amino groupsare known from DE-OS No. 25 30 819.

Their effect is not yet good enough for practical requirements.

It has now been found that phenolic resins obtained from alkyl orcycloalkylphenol, aldehyde, polyamine and polyether show a tackifyingeffect superior to that of known phenolic resins.

Accordingly, the present invention relates to phenolic resins obtainedby condensation from alkylphenol, aldehyde, polyamine and polyether in amolar ratio of 1:0.7 to 1.3:0.005 to 0.2:0.001 to 0.3.

The reaction mixture is condensed by heating the reaction componentstogether to 95° to 180° C. under pressures of from 1 to 7 bar. Thereaction may be carried out in the presence of solvents, such astoluene, xylene or other water-immiscible or only partly water-misciblesolvents. However, condensation is preferably carried out in the absenceof solvents. The reaction may be catalyzed by acids, for example byp-toluene sulfonic acid, oxalic acid or acetic acid.

Preferred alkylphenols are those containing straight-chain or branchedC₁ -C₁₅ alkyl or C₃ -C₁₅ cycloalkyl groups in the o- or p-position.Monoalkylphenols containing branched C₄ -C₉ alkyl groups areparticularly preferred.

Suitable aldehydes are formaldehyde and aliphatic aldehydes containingfrom 2 to 6 carbon atoms, for example acetaldehyde, propionaldehyde,butyraldehyde, croton aldehyde or mixtures thereof.

Formaldehyde may be used in the form of paraformaldehyde, trioxane oraqueous formalin solution, the last form being preferred.

The polyamine component may be, for example, an aliphatic orcycloaliphatic polyamine containing at least two primary amino groups.

Examples are diprimary alkylenediamines containing at least 2 andpreferably from 2 to 14 carbon atoms, such as ethylenediamine, 1,2- or1,3-propylenediamine, di-1,2-propylenetriamine,di-1,3-propylenetriamine, tetramethylenediamine, pentamethylenediamine,hexamethylenediamine, octamethylenediamine; polyethylenediaminescorresponding to the formula H₂ N--CH₂ CH₂ (NHCH₂ CH₂)_(b) --NH₂, whereb is an integer of from 1 to 150, such as diethylenetriamine,triethylene tetramine and tetraethylene pentamine;polyoxyethylenediamines, polyoxypropylenediamines,3-(2-aminoethyl)-aminopropylamine, 1,2-bis-(3-aminopropylamino)-ethane,N,N'-bis-(3-aminopropyl)-1,4-diaminobutane and4,7,10-trioxatridecane-1,13-diamine; cycloaliphatic and heterocyclicamines containing above all nitrogen atoms in the ring, such as forexample 1,2- or 1,3-diaminocyclopentane, 1,2-, 1,3- or1,4-diaminocyclohexane, 3,3'-, 3,4'- or 4,4'-diaminodicyclohexylmethane,2,2-bis-(4'-aminocyclohexyl)-propane,4,4'-diamino-3,3'-dimethyldicyclohexylmethane,3-aminomethyl-3,5,5-trimethylcyclohexylamine (isophorone diamine),N,N'-bis-(3-aminopropyl)-piperazine, N,N'-bis-(2-aminoethyl)-piperazine,1,3- and 1,4-bis-(aminomethyl)-cyclohexane and3(4),8(9)-bis-(aminomethyl)-tricyclo[5,2,1,0².6 ]decane.

It is preferred to use polyamines corresponding to the following formula

    H.sub.2 N--[(CH.sub.2).sub.n --NH].sub.m --(CH.sub.2).sub.n --NH.sub.2

in which

n=2, 3 and

m=3 to 150, preferably 3 to 8,

for example tetraethylene pentamine, pentaethylene hexamine,hexamethylene heptamine and mixtures thereof.

The polyethers preferably correspond to the following formula ##STR1##in which R¹, R² and R³ represent hydrogen or C₁ -C₁₂ alkyl,

q, r, s are integers of from 0 to 300,

A represents hydrogen, --OH, --OR⁴, --OCOR⁴, NHCOR⁴ and

R⁴ represents alkyl, aryl or aralkyl and the sum of q, r and s is atleast 2.

Preferred polyethers correspond to the following formula ##STR2## inwhich R¹, R² and R³ represent hydrogen or methyl and

q, r and s are integers of from 0 to 200 and the sum of q, r and s is atleast 2 and preferably at least 5.

The tackifying resins according to the invention are preferably preparedby initially introducing the mixture of alkylphenol, polyamine andpolyether and, after adding the aldehyde, heating for 3 to 5 hours to95° to 100° C. Thereafter, water is first removed by azeotropicdistillation, for example with aromatic solvents, such as toluene orxylene, after which excess phenol is distilled off first under normalpressure and then in vacuo at 120° 180° C. In a preferred process forisolating the resin, the resin solution is worked up after azeotropicremoval of the water using a tubular coil evaporator jacketed by amedium heated to a temperature of up to 180° C.

The softening point of the resins obtained is in the range of from 50°150° C. The resins have an average molecular weight of from 800 to 4000(weight average determined by gel chromatography).

The resins according to the invention are excellent tackifiers forelastomers, such as natural rubber (NR), styrene-butadiene copolymer(SBR), acrylonitrile-butadiene copolymer (NBR), polybutadiene (BR),polychloroprene (CR), polyisoprene (IR), isobutylene-isoprene copolymer

i (IIR), ethylene-propylene terpolymer (EPDM) and mixtures thereof. Theresin is present in the rubber mixture in a quantity of from 0.3 to 8%by weight and preferably in a quantity of from 1 to 6% by weight, basedon the weight of the rubber. The resins are incorporated by mixing inthe usual way.

The resins have a tackifying effect on a variety of different mixtures,such as hose mixtures, rol-er mixtures, tire mixtures, fabricationmixtures, molding and injection mixtures, to which fillers, such ascarbon black, kaolin, silicas or plasticizers, may optionally be added.

No adverse effect upon the processing properties of the rubber mixturescontaining the tackifying resins in the usual quantities could beobserved.

The tackifying effect was evaluated by a method developed by Applicantsthemselves instead of the usual method. In this method, the timerequired for two surfaces to separate under a constant load (principleof a creep test) is measured. This time is directly proportional to thetackifying effect and is a direct measure of tackiness.

Tackiness test

The two ends of a strip-form test specimen measuring 150×20×2 mm arepressed together for 30 seconds over an area of 20×10 mm under aspecific pressure of 3.5 MPa after the strip-form test specimen had beenformed into a ring at its ends in such a way that the two sides coatedwith rubber mixture lay on top of one another. The ring thus formed isplaced over a free roller. Another movable roller to which differentweights may be applied is then suspended in the lower loop. After theload roller has been suspended, the time which it takes the two joinedcontact surfaces of the test specimen to separate completely from oneanother is determined (the test is terminated after 300 seconds).

Preparation of the rubber mixtures and test specimens

The mixtures mentioned in the following Examples, of which thefabrication tackiness is to be measured, were mixed in a kneader by themethod and in the order normally used in the rubber industry, thetackifying resins and vulcanization accelerators being subsequentlyincorporated on the mixing rolls.

The test mixtures were drawn out into sheets 1.2 to 1.3 mm thick, thesheets thus formed were placed after storage for 24 hours on a cottoncloth (300×300 mm) coated with polychloroprene adhesive and, after thesurface of the mixture had been covered with tracing cloth and thesurface of the fabric with cellophane in a 300×300×2 mm frame, thesheets were placed between steel plates and pressed for 5 minutes at110° C. in a standard multiple-platen press (working pressure 200kp/cm²). Test specimens measuring 150×20 mm were punched out of theplates thus obtained.

Before tackiness was measured, the tracing cloth was removed and bothends of the test strip coated with n-hexane hexane over an area of 20×10mm. After evaporation, the test specimens were looped together to form aring in the manner described above and tackiness measured.

EXAMPLE 1

154 g 35% formalin are added at 90° C. to a mixture of 335 gp-tert.-butylphenol, 16.8 g octaethylene glycol and 22.5 g pentaethylenehexamine. After heating for 4.5 hours to reflux temperature, first thewater is distilled off at an internal temperature of up to 150° C.,followed by all other volatile constituents in a water jet vacuum up to170° C. Approx. 350 g of a reddish-brown, solid resin are obtained.Softening point 130° C., M_(w) =1400.

EXAMPLE 2

154 g 35% formalin are added at 90° C. to a mixture of 335 gp-tert.-butylphenol, 6.72 g octaethylene glycol and 22.5 g pentaethylenehexamine, after which the reaction mixture is heated for 4.5 hours toreflux temperature. The reaction product is worked up in the same way asin Example 1. Softening point 135° C., M_(w) =1200.

EXAMPLE 3

365 g 35% formalin is added at 90° C. to a mixture of 910 gp-tert.-octylphenol, 45 g pentaethylene hexamine and 36.4 g polyethyleneoxide (M_(w) 800), after which the reaction mixture is heated for 4.5hours to reflux temperature. The reaction product is worked up in thesame way as in Example 1. Softening point 70° C., M_(w=) 1800.

EXAMPLE 4

72.5 g 37% formalin is added at 90° C. to a mixture of 167.5 gp-tert.-butylphenol, 11.25 g polyethylene imine (M_(w) 10,000) and 8.4 gof a nenylphenol ethoxylated with 10 times the molar quantity ofethylene oxide, after which the reaction mixture is heated for 4.5 hoursto reflux temperature. The reaction product is worked up in the same wayas in Example 1. Softening point 88° C., M_(w) =1500.

The test mixture has the following composition:

    ______________________________________                                        Emulsion-SBR         103.0   parts by weight                                  Polybutadiene        25.0    parts by weight                                  Zinc oxide           5.0     parts by weight                                  Carbon black N 220   75.0    parts by weight                                  Aromatic mineral oil plasticizer                                                                   12.0    parts by weight                                  Stearic acid         2.0     parts by weight                                  Sulfur               1.8     parts by weight                                  Benzthiazyl-2-cyclohexyl sulfenamide                                                               1.2     parts by weight                                  Tackifier            4.0     parts by weight                                  ______________________________________                                                                  Separation Load                                     Test  Tackifier           time (secs.)                                                                             (g)                                      ______________________________________                                        a     Example 1           >300       250                                      b     Example 2           228        250                                      c     Example 3           128        375                                      d     Example 1, DE-OS 25 30 819                                                                         40        375                                      e     Example 3           139        500                                      f     Example 3 without polyether,                                                                       96        500                                            DE-OS 25 30 819                                                         ______________________________________                                         Explanations:                                                                 a The separation times are average values of 5 measurements.                  b The chain lines are intended to identify the individual mixtures.           Comparisons should only be made within the same mixture.                 

We claim:
 1. A phenolic resin obtained by condensing(a) an o- or p-C₁ -C₁₅ -alkyl or --C₃ -C₁₅ -cycloalkylphenol, (b) an aliphatic C₁ -C₆ -aldehyde, (c) a polyamine corresponding to the formula H₂ N--[(CH₂)_(n) --NH]_(m) --(CH₂)_(n) --NH₂ in whichn=2 or 3 and m=3 to 150, and (d) a polyether corresponding to the formula ##STR3## in which R¹, R² and R³ represent hydrogen or C₁ -C₁₂ -alkyl,q, r and s are integers of from 0 to 300, A represents hydrogen, --OH, --Or⁴, --OCOR⁴, NHCOR⁴ and R⁴ represents alkyl, aryl or aralkyl and the sum of q, r and s is at least 2, in a molar ratio a:b:c:d of 1:(0.7 to 1.3):(0.005 to 0.2) : (0.001 to 0.3) at 95° to 180° C. and under a pressure of 1 to 7 bar.
 2. A phenolic resin as claimed in claim 1, wherein the aliphatic aldehyde is a monalkyl phenol containing branched C₁ -C₉ alkyl groups.
 3. A phenolic resin as claimed in claim 1, wherein the polyamine is an aliphatic or cycloaliphatic compound containing at least two primary amino groups.
 4. A phenolic resin as claimed in claim 1, wherein R¹, R² and R³ represent hydrogen or methyl, q, r and s are integers of from 0 to 100 and A represents OH.
 5. A process for the production of phenolic resins according to claim 1 characterized in that the alkylphenol, aldehyde, polyamine and polyether are condensed in a molar ratio of 1:(0.7 to 1.3):(0.005 to 0.2):(0.001 to 0.3) at 95° to 180° C. and under a pressure of 1 to 7 bar. 